We propose to investigate mortality and morbidity at the oldest ages in Drosophila melanogaster, an experimental system that is well-suited to laboratory analysis and genetic manipulation. Specific aims are: 1) QTL Mapping- We will estimate the number, chromosomal location, and magnitude of effects of genes that cause variation in longevity using DNA-based genetic markers. 2) Demography of Genes- We will estimate age-dependent mortality parameters for small chromosomal segments carried in genetically homogeneous recombinant inbred lines. 3) ADL Experiments- We will characterize age-dependent disability in cohorts of genetically homogeneous flies, and estimate the genetic correlation of mortality and morbidity across genotypes. Notable features are: (i) The experiments emphasize large scale data collection for estimation of genetic and demographic parameters. (ii) QTL mapping experiments employ some of the most recent developments in DNA technology (PCR and RAPDs). (iii) Data will be informative about the genetic basic of male-female correlations. (iv) Data will be archive for general access. Health relevance: The research will provide information about the plasticity of morbidity and mortality at the oldest ages in a model experimental system.